Xerographic toner dispenser



June 5, 1968 R. H. EICHORN XEROGRAPHIC TONER DISPENSER 2 Sheets-Sheet 1 Filed Oct. 22, 1965 INVENTOR. ROGER H. EICHORN B e 4% ATTORNEYS June 1968 R. H. EICHORN XEROGRAPHIC TONER DISPENSER 2 Sheets-Sheet 2 Filed Oct. 22, 1965 FIG. 3

ROGER H EICHORN ATTORNEYS United States Patent 3,389,863 XEROGRAPHXC TONER DISPENSER Roger H. Eichorn, Webster, N.Y., assignor to Xerox Corporation, Rochester, N.Y., a corporation of New York Filed Oct. 22, 1965, Ser. No. 500,826 3 Claims. (Cl. 241-94) ABSTRACT OF THE DISCLOSURE A device for dispensing toner from solid blocks having a container to hold the block and bias the same against a series of blades which are reciprocated to separate tone particles from the blades.

This invention relates to apparatus for handling and dispensing xerographic toner material and particularly to apparatus for dispensing xcrographic toner material from a solid block.

More specifically, the invention relates to an improved xerographic toner dispenser that is particularly suitable for dispensing toner powder that has been compacted into a block. In xerography, latent electrostatic images are developed on photoconductive plates by bringing powder or toner particles into the field of attraction of an electrostatic charge which forms an image on the plate surface. The toner powder used to develop the image must be periodically replaced in the developer system.

Development of xerographic images is usually accom plished with developers which comprise, in general, of a mixture of a suitable pigmented or dyed electroscopic powder, herein referred to as toner, and a granular carrier material which functions to carry the toner and to generate triboelectric charges on the toner. In the development of the image, the toner is brought into surface contact with the coating on the xerographic plate and is held thereon electrostatically in a pattern corresponding to the electrostatic latent image. Thereafter, the developed xerographic image is usually transferred to a support material to which it may be fixed by any suitable means.

In the mixture of toner particles and carrier material, the toner particles which are substantially smaller than the carrier particles adhere to and coat the surface of the carrier particles as a result of the electrostatic attraction between them. During development, as the powder coated carrier particles come in contact with the xerographic plate, the toner is attracted from the carrier to the plate surface and is held by the electrostatic charge in the image areas. The partially denuded carrier particles pass off the plate surface back to the mixture of carrier and toner material where it again picks up toner particles.

As toner powder images are formed, the toner consumed must be replenished to the developer mixture substantially in proportion to the amount consumed. The means used to dispense the toner to the developer mixture is very important to the development of the xerographic image. If the toner concentartion in the developer mixture is too great, then the xerographic images produced will have heavy deposits of toner in image areas and also in non-image areas giving a gray veiling to the final print. If the developer mixture has an insuffic ient amount of toner, then there will be low contrast between the Xerographic image and the background areas giving a poor quality of final print. In order to maintain the correct amount of toner material in the developer mixture, it is necessary that the toner dispenser accurately provide desired amounts of toner upon each actuation of the dispenser.

Toner powder or material is not readily adaptable to conventional types of dispensing techniques. For example,

ice

toner is constructed of pigmented resins which are plastic in nature and which may include plasticizing additives, such as waxes or low melting resins, which tend to increase the agglomeration characteristics of the material. That is, the toner, when allowed to sit or when subjected to agitation or heat, tends to ball up or lump together in a mass. This characteristic tends to make dispensing or handling of the material extremely difficult. Also, toner materials are usually black in color and extremely dusty or dirty. Handling of the material in the powder form has always been a problem since the size of the particles is so small that there tends to be produced clouds of the material Whenever it is moved about in the open atmosphere. For example, when the toner is dumped from a can or container into the toner dispenser, a certain amount of dust or powder gets into the air producing a cloud of dirt or dust. These objectionable characteristics are eliminated when the toner is compacted into a solid block for handling and storage purposes and dispensed directly from the block to the developer system.

It is therefore an object of this invention to improve xerographic toner dispensers to dispense toner from solid blocks.

It is also an object of this invention to improve toner dispensers used in automatic xerographic machines.

It is also an object of this invention to separate individual particles 'of toner from a block made up of toner particles compressed together.

These and other objects of this invention are attained by means of a toner dispenser suitable for holding blocks of solid toner and having a series of blades which are movable across the surface of the blocks of the toner to scrape or separate individual toner particles therefrom.

For a better understanding of the invention as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a schematic right side sectional view of the machine showing the invention;

FIG. 2 is a perspective view of the xerographic drum, developer unit and toner dispenser of the machine shown in FIG. 1 with portions broken away to show internal construction; and

FIG. 3 is a fnont view of the toner dispenser shown in FIG. 2.

The xerographic machine shown in FIG. 1 has a front opening 16 to receive an original document to be reproduced, and an opening 18 into which copy paper or support material is fed to receive a powder image. After an image has been transfered to the copy paper, the paper emerges from a slot 20 in the top cover 14.

A xerographic drum 22 having a layer of photoconductive material 23 about its outer surface is mounted for rotation on a shaft 24. As the drum 22 rotates, it moves past a charging station 26 wherein a uniform electrostatic charge is placed on the photoconductor 23 by means of a corotron 28. The drum then rotates past an exposure station 30 and a developer station 32. At the developer station 32, a powder image is formed corresponding to a latent electrostatic image created on the drum surface at the exposure station. The light image at exposure station 30 discharges the drum in areas of light and leaves the drum an insulator in areas of darkness thereby creating an electrostatic latent image on the drum surface. As the drum rotates through the developing station 32, a paddle wheel 34 im-pels developer material 36 against the surface of the drum 22. The developer material is composed of a granulated carrier bead and resinous powder or toner material used to develop the electrostatic images. The toner material is triboelectrically 'held on the carrier beads and is electrostatically attracted away from the carrier beads to the areas containing the latent electro-.

static image, thereby developing a powder image.

The drum continues to rotates past a transfer station 38 having a transfer corotron 40 and a drum cleaning station 42 having a precleaned corotron 44 and a web cleaner 46. The powder image on the drum surface is transferred to a sheet of paper or support material at the transfer station 38. The transfer corotron 40 is positioned to provide an electrostatic charge on the back of a belt 48. The belt 48 is of dielectric material and moves in a continuous loop so that sheets of paper will be carried into contact with the surface of the drum 22. A sheet of paper inserted in the opening 18 is forced forward past an electrostatic charging device 49 until it trips a switch LS-l. The switch LS-l turns on the corotron 49 which tacks the paper to the belt. The transfer corotron 40 then applies a charge to the back of the belt. The electrostatic charge placed on the back of the belt by the electrostatic charging device or corotron 40 attracts the powder image from the drum surface to the surface of the paper. The paper is then carried forward past a fuser 50 wherein the powder is heated and caused to coalesce and bond to the surface of the paper. The paper is gripped by a pair of ejection rollers 52 and driven forward against a deflection guide 54 which curves the paper upwards and out slot to the top of the machine.

The toner powder used herein has a negative charge relative to the various charges used to create the latent electrostatic images and to transfer the powder from the drum to the support material surface. The latent electrostatic image is created from the positive charge that is placed on the surface of the xerographic drum by the corotron 28. The negative charged toner is attracted to the positive latent electrostatic image. At the transfer station, the transfer corotron places another positive charge on the back of the transfer material and the belt 48 so that the negative toner material is then attracted to the surface of support material.

The drum cleaning station 42 has a cleaning roller 56 which forces a web of fibrous material 46 into surface contact with the rotating xerographic drum. The residual powder which has not been transferred to the sheet of paper or support material remains on the drum surface and must be removed prior to the creation of a new image on the surface of the drum. The powder material is held on the drum surface by electrostatic charges which originally were used to create the image and residual electrostatic charges in non-image areas. The eifect of these electrostatic charges is neutralized by the use of the pre clean corotron 44 which deposits a uniform electrostatic charge of opposite polarity to that holding the toner on the surface of the drum. The fibrous web material 46 is taken from a supply roll 58 around the cleaning roll 56 into contact with the surface 23 of the drum 22 and onto a take-up roll 60. The surface of the xerographic drum is then exposed to a spot of light 62 which discharges the drum surface, removing any residual electrostatic charges which may exist on the drum surface.

The original copy to be reproduced is positioned on a counter 64 and inserted into the document opening or slot 16. The document slides forward, deflecting switch actuator 66 of a limit switch until it encounters the document positioning stop 68. With the document abutting against the stop 68, it overlies a feed belt system 70 and is beneath a feed roller 72. When the machine is in operation, as described below, the feed roller 72 comes down on the document, forcing it against the feed belt 70 and driving it forward. The stop 68 which is mounted on a shaft 74 is rotated in a counterclockwise direction as seen in FIG. 1, deflecting the front end of the document down along the path of the feed belt 70. The belts 70 are constructed of a dielectric material and the document is held in contact with the belts 70 by a row of leaf spring-type guides 76 which extend across the conveyor system. The document is electrostatically tacked to the belt 70 by electrostatic 4 charge applied to the document surface by a corotron 78.

The feed roll belts 70 extend around belt rollers 80 and are held in tension by a pair of guide rollers 82, one of which is adustable to vary the tension on the belts 70. The documents are carried by the belts 70 past scanning station 84 where they are illuminated bya pair of lamps LMP-l. Thedocuments are carried down between the belts 70 and a lower roller 86 at the same speed as the surface of the xerographic drum and then ejected through a slot 88 at the bottom front of the machine. The belts 70 and the documents held thereon are flat against a backup platen 90 at the scanning station. The backup platen 90 is white at the scanning station to reflect any light passing through the document back through the document to the xerographic drum 22.The lamps LMP-l are housed in a housing 92 and shielded from the document by a transparent plate 94.

An optical image of the illuminated portion of the document at the exposure station 84 passes through the transparent plate 94, through an opening 96 in the lamp housing 92 to a combination mirror-lens assembly 98. The latent image passes through the lens 102 and is reflected by a mirror surface 104 back through the lens 102 to a mirror 106. The lens 102 focuses the image so that the image is properly focused on the drum surface 22 when it is reflected by the mirror 106 through the exposure slit 108 at exposure station 30 to the drum surface 22. The light path of the optical image is indicated generally by the dotted line 110.

The xerographic machanism is shielded from the ambient light produced by the exposure system by means of a shield 112. The light shield 112 has an opening 114 positioned between the mirror 106 and the exposure slit 108 to allow passage of the light image to the drum surface. There is also an opening 116 in the light shield 112 which permits some of the ambient light to pass through the shield and be reflected by a reflective surface 118 to the drum to produce the discharge spot 62. The light of the discharge spot 62 removes any residual charge remaining on the drum surface after drum cleaning by rendering the photoconductive surface conductive and draining off any remaining charge.

The development system used to develop the latent electrostatic images on the side of the drum which is moving from bottom to top is a paddle wheel developer. A rotatable shaft 120 having a series of paddles 122 extending outward from the periphery thereof constitutes the paddle wheel 34. The paddle wheel 34 extends across the length of the drum 23 and is contained within the developer housing 124. This type of developer is also shown in FIGS. 2 and 6. The developer housing 124 extends from a point just past the exposure station 30 in the direction of movement of the drum to a point further along in the direction of rotation of the drum. The housing is shaped to contain a quantity of developer material 36 in contact with the paddle wheel 34. The developer 36 consists of carrier beads and toner particles intimately mixed so that a triboelectric charge causes the toner particles to adhere to the carrier beads. As the paddle wheel 34 rotates in the direction indicated by the arrow, the developer material is hurled or thrown by the paddles 122 upwards against the surface 22 of the drum 23. p

Developer is prevented from passing between the drum surface and edge of the developer housing 124 by means of a drum'seal 126. The seal 126 consists of a piece of nonconductive, nonabrasive material mounted on the edge of the housing 124 in contact with the surface of the xerographic drum. The seal 126 prevents carrier beads from escaping from the developer housing 124. At the time that the drum passes the edge of the housing, there is an electrostatic image on the surface which must be protected. Any seal used at this point must not only protect the electrostatic image but must also be free from any injurious effects to the photoconductive surface. Also, these characteristics of the seal must not change appreciably after extended use. For example, the seal cannot become abrasive or conductive after toner has had an opportunity to accumulate on the surface. A thin strip 127 of polyethylene terephthalate, sold under the trademark Mylar, of about .003 inch thickness is secured to a clamping member 129 mounted on the housing 124. The strip 127 extends into contact with the drum 22. Alternatively, the strip 127 may be constructed of polyurethane or fibrous web material of the type used in the web cleaner.

As the developer encounters the surface of the drum, portions of the toner material are jarred loose from the carrier beads and are attracted by electrostatic charges on the drum surface. The electrostatic charges on the drum surface define the images to be reproduced, and thus the powder particles held on the drum surface by the electrostatic charge are in image configuration. The carrier beads continue upward in their path of travel and eventually fall back into the lower portion of the developer housing 124 to be remixed with the main body of developer material. As toner particles are removed by the electrostatic charge on the drum surface, additional toner must be added to the main body of developer material. A toner dispenser 128 is mounted in the top of t e developer housing 124 for the purpose of supplying additional toner material as needed. The toner dispenser 128 consists of a container portion 130 adapted to hold solid blocks of toner material 132, a pressure cap 134 and a scrapping blade 136. The blocks of toner 132 are placed in the container 130 with one edge against the blades 135. The cap 134 is also placed inside the container 130 against the blocks 132 and is held in place and forced forward by a series of leaf springs 138. The leaf springs 138 are mounted on brackets 140 on the front cover 142 of the apparatus. As the cover 142 is closed, the leaf spring 140 is forced against the cap 134 urging the solid blocks of toner 132 against the blades 136.

Operation of the toner dispenser can best be seen in FIGS. 2 and 3. The blades 136 are similar to hack saw blades bent in a honeycomb configuration to insure complete coverage of the surface of the toner blocks and mounted in a pair of end blocks 144. The end blocks 144 are supported in the machine frame plate by means of a pair of sliding pins 146 at one end and a single pin number 148 at the other end. The pin 148 has a button or cap 150 mounted on one end so that it extends outside of the entire machine. A compression Spring 152 is mounted on the shaft 148 between the cap 150' and a bearing plate 154. Pressure on the cap 152 forces the pin 148 and the blades 136 forward against the action of the spring 152. The movement of the blades 136 across the surface of the block 132 produces a scrapping action which removes portions of the toner material from the block which then fall into the bottom of the developer housing 124. When the cap 150 is released, the spring 152 returns the springs 136 to their original position again producing a scrapping action on the surface of the blocks 132 and removing toner therefrom.

A conveyor belt 48 is positioned to carry a sheet of paper from the copy paper opening 18 into contact with the xerographic drum 23 and then-to the fuser 50 and ejection rollers 52. The belt 48 extends around a roller 156 just inside the copy paper opening 18 and a spring loaded tensioning roller 158 positioned just ahead of the heat fuser 50. As the belt extends between the rollers 156 and 158, the bottom surface thereof is in contact with the top of the xerographic drum 23. The roller 158 is journaled in a bifurcated member 160 and is spring loaded by compression spring 162. The bifurcated member 160 is mounted on and pivoted about a shaft 164 so that rotation of the shaft 164 will elevate the roller 158 and the belt system 148 away from the drum 23. When a sheet of paper is inserted in the opening 18 on counter 166, it slides forward until it is gripped between a pressure roller 168 and the belt 48 at roller 156. The paper is carried forward in contact with the belt to a point just Cir beyond an electrostatic discharge member or corotron 49. The belt 48 is held flat at this point by a guide 170 mount ed against the inside surface of the belt. The corotron 49 is energized when the paper hits switch LS-1 and placed an electrostatic charge on the paper surface, in this case a positive charge, causing the paper to adhere to the belt. The electrostatic attraction between the paper and the belt causes the paper to be carried forward with the belt into surface contact with the xerographic drum and had a powder image transferred thereto, it is carried forward to the heat fuser 50 and is separated from the belt 48 by the sharpness of the angle that the belt takes around the roller 158. The sharpness of the angle and the natural rigidity of the paper are sufiicient to overcome the electrostatic attraction between the belt and the paper, and thus the paper continues forward while the belt is directed around the roller 158.

. The transfer corotron 40 mounted above the belt 48 at the top of the drum or transfer point 38 is tilted at a slight angle such that the electrostatic charges placed on the belt directly above the transfer point and not preceding the transfer point. When the electrostatic charge is placed on the belt slightly before the transfer point, the electrostatic image on the drum surface tends to produce an arc between the drum and the belt; and the powder image on the drum surface is disrupted or destroyed. Tilting the transfer corotron 40 in the manner shown in FIG. 1 eliminates the arcing prior to the transfer process.

In operation, blocks of toner are inserted in the toner dispenser substantially as shown in FIG. 2. The front of the machine is opened, that is, the front plate 142 is pivoted away from the toner dispenser; and the springs 138 are withdrawn from the cover 134. With the springs 138 withdrawn, the cover 134 is removed; and the block toner 132 may be inserted in the toner dispenser. The cover 134 is then replaced, forcing the blocks of toner forward against the blades 136. When the front of the machine is closed, the springs 138 urge the cover 134 and the toner 132 forward against the blades 136. Actuation of the button 150 against the bias of the spring 152 causes the blades 136 to be moved across the surface of the toner blocks 132. The action of the blades 136 back and forth across the face of the toner blocks causes particles of toner to be separated from the block and permitted to drop down into the developer housing 124. Each of the blades 136 has a saw toothed edge in contact with the toner blocks. The action of the blades across the surface of the toner could either be manual as shown herein or made automatic by having the shaft 148 oscillated in synchronism with the movement of the xerographic drum or the development system.

While the invention has been described with reference to the structure disclosed herein, it is not confined to the details set forth; and this application is intended to cover such modifications or changes as may come within the purpose of the improvements or the scope of the following claims.

What is claimed is:

1. A xerographic toner dis enser for use in dispensing toner from solid blocks including a container open at two ends and adapted to receive blocks of toner,

a series of saw toothed blades extending across one of the open ends of the container, said blades being formed of at least one pair of blades having high and low points, each one of the pair of blades being connected to each other at said high point and said low point,

a cover adapted to fit into the other end of the container and rest against the toner blocks in the container,

biasing means positioned to urge the cover into the container against the blocks so that the blocks press against the blades,

7 n 7 v and means to. move the blades in a reciprocating manner across the surface of the toner blocks to thereby separate individual toner particles. 2. A xerographic toner dispenser for use in dispensing toner from solid blocks into a xerographic developer unit including l t v 1 a container adapted to hold blocks of toner and having one end extending into the developer unit, the end of the container extending into the developer unit being open and having a series of saw toothed blades extending across the end thereof, said blades being formed of at least one pair of blades having high and low points, each one of the pair of blades being connected to each other at said high point and said low point, means mountable in the other end of the container to bias toner blocksin the containertowards the saw toothed blades, and means to move the blades in a reciprocating manner across the opening in the container and in contact With the toner blocks to thereby separate individual toner particles from the toner blocks. 3. A Xerographic toner dispenser for use in dispensing toner from solid blocks including a container opened at two ends and adapted to receive blocks of toner, v means mounted at one end to bias the blocks of toner towards the opposite end, means mounted at the other end to restrain the toner blocks and to provide an abrasive surface for separating individual particles of toner from the block, said abrasiverneans being formed of at least one pair of blades having high and low points, each one of the pair of blades being connected to each other at said high point and said low point, and biasing means to move the abrasive means to separate individual toner particles from the toner block. 15 References Cited UNITED STATES PATENTS 1,048,919 12/1912 Van Wye 146-178 2,215,962 9/1940 Herrnann 241-94 X 90 2,342,213 2/1944. Ostrander 24l94 d 2,349,017 5/1944 StOrer l46178 X FOREIGN PATENTS 241,645 12/1911 Germany.

25 JAMES M. MEISTER, Primary Examiner. 

